Snowmobile chassis

ABSTRACT

The front end ski post supporting structure is a single piece aluminum casting and the frame is fabricated from welded aluminum extruded and sheet stock. The design is modular in that the same components can be readily modified to make a 15, 18, or 21 inch chassis.

ite States Patent 1191 Woods Oct. 8, 1974 SNOWMOBILE CHASSIS 3,613,20510/1971 Takada 296/29 [75] Inventor: John A. Woods, Milwaukee, Wis.

. Primary Examiner-Allen N. Knowles [73] Asslgnee a Incorporated WhltePlams Attorney, Agent, or Firm-George W. Price; Walter Lewis [22] Filed:July 9, 1973 [521 [LS Cl 180/5 R 296/29 The front end ski postsupporting structure is a single [51] Int 1362; 27/00 piece aluminumcasting and the frame is fabricated [58] Field 296/29 from weldedaluminum extruded and sheet stock. The

design is modular in that the same components can be [56] ReferencesCited readily modified to make a l5, 18, or 21 inch chassis.

UNITED STATES PATENTS 11 Claims, 6 Drawing Figures 3,608,658 9/1971Woodfill [80/5 R SNOWMOBILE CHASSIS This invention relates tosnowmobiles, and more particularly, to improvements in snowmobilechassis frames and front end ski post supports.

Briefly, the invention provides a modular frame and modular front endski post support which give increased flexibility and economy ofmanufacture and increased strength and weight reduction.

In the ensuing description the improved snowmobile chassis is describedas utilizing aluminum. However, it will be understood that other metalssuch as lightweight magnesiums are within the scope of the invention andencompassed thereby.

The preferred form of the invention will be described with particularreference to the attached patent drawings in which:

FIG. 1 is a perspective view of the invention;

FIG. 2 is a top plan view;

FIG. 3 is a side elevation view;

FIG. 4 is a rear view;

FIG. 5 is a front view; and

FIG. 6 is a cross-sectional view of one of the side panels.

In the preferred form of the invention the snowmobile chassis comprisesa modular frame 10 and a modular front end ski post support 11. Both areconstructed from aluminum or other lightweight metals such as magnesium.The modular frame 10 is fabricated from extruded and sheet stock,whereas the modular support 11 is a casting.

In particular, the modular support 11 is a generally U-shaped castinghaving integral sides 12 and a front facing bite portion 13. The sides12 are adapted to be connected to the front end of side panels 14 of themodular frame 10 by rivets 15 (see FIG. 3) or the like.

Integral ski post supporting front diverging arms 16 are formed at thecorners of the U-shaped casting 11. Their front extremities haveintegral tubular bearing portions 17 formed therein. As will be obvioustothose skilled in the art, the tubular bearings 17 are adapted toreceive the posts of not shown front end ski runners of the snowmobile.

Inasmuch as the sides 12 of the casting l1 and the side panels 14 of theframe 10 are connected to each other-by rivets 15 or the like, these twoparts 12 and 14 reinforce each other. In addition, they have alignedbearing apertures 18 formed therein at each side of the chassis. Thesebearing apertures 18 are adapted to support the not shown snowmobilebelt drive shaft therein.

As heretofore stated the front end ski post support 11 is modular, andthis is so since it is conceived and designed so as to be adapted to fit15, 18, or 21 inch width frames 10. This is aecomplishable in thecasting by using not shown inserts in the casting mold to selectivelyincrease or decrease the width of the casting so as to match it up withthe selected size of the modular frame, as will be more clearhereinafter. I-Ieretofore the front end ski post support was built upfrom a plurality of pieces of welded or riveted steel stock which wasmore expensive to fabricate and did not give a modular front end skipost support as in the instant invention, nor the advantage of lighterweight with increased strength, as will be further describedhereinafter.

The chassis frame 10 is tunnel shaped and in concept and designcomprises a minimum number of separate pieces connected together in sucha manner that a modular frame of varying size is readily obtainable.Specifically, there are two extruded lightweight metal side panels 14, atop sheet 19, and a back sheet 20 (see FIG. 4). The top sheet 19 can beof lighter guage than the side panels 14 since it has integraltransverse reinforcing corrugations 21 formed therein. The back sheet 20is connected to both the side panels 14 and the top sheet 19 by rivets22 (see FIGS. 2 and 3) or the like to reinforce the rear end of thetunnel frame 10.

Two running board sheets 23 are also provided for the frame. These areconnected to the lower portions of the side panels 14 by spot welds 24(see FIG. 2) or the like. The top sheet 19 is connected to the upperportions of the side panels 14 by spot welds 25 (see FIG. 2) or thelike.

The snowmobile frame 10 is modular since it can be easily converted to a15, 18, or 21 inch width tunnel merely by varying the width of the topsheet 19 and back sheet 20. The other parts of the modular frame 10 suchas side panels 14 and running boards 23 are constant. In other words, itis very easy to vary the selected width of the chassis and match up theframe 10 and front support 11 with each other. Heretofore, this was notpossible to achieve at a low manufacturing cost since the frame was alarge single piece steel stamping. The steel stamping was also heavierthan the fabricated aluminum or magnesium modular frame of the instantinvention, and not as strong, and also required much more storage orinventory space. In the instant invention it is very easy to stock thepieces 14, 19, 20, 23 separately or partially assembled in a smallerarea than the prior art frames and then finish the assembly depending onthe size chassis desired.

Referring now to FIG. 6 for a more detailed description of the parts,the side panels 14 have inwardly and outwardly directed integralshouldered ledges 26 and 27 formed at the upper and lower portionsthereof respectively. The ledges 26 and their shoulders 26 serve to nestthe opposite edges of the top sheet 19 to the side panels 14 so they arealigned together for connection together by the welds 25. The runningboard sheets 23 are similarly aligned with the side panels 14 forconnection together by the welds 24. The ledges 27 have end shoulders 27and in addition, overhanging spaced ledges 28 are integrally formedalong the ledges 27. The ledges 27 and 28 are spaced by a distanceequivalent to the thickness of the running board sheets 23. The inneredges of the running board sheets are adapted to be nested between thespaced ledges 27 and 28. The outer edges of running board sheets 25 arecurled so as not to present a sharp outer edge.

The spot welds 25 and 24 (see FIG. 2) connecting the top sheet 19 .andrunning board sheets 23 to the side panels 14 are formed in the ledges26 and 27 respectively. The running board sheets 23 also have integralupwardly sloped front foot rest portions 23 These foot rest portions 23are also connected to the side panels 14 by spot welds or rivets.

Still referring to FIG. 6, an overhangingshoulder 26" is formed at theupper outer corners of the side panels 14. The shoulders 26" andoverhanging ledges 28 serve to nest or align the front casting 11 withrespect to the frame 10.

It should be noted that the welding of parts 14, 19, and 23 can bereadily accomplished in a welding jig. Also, the parts can be storedpartially preassembled. That is to say, the running board sheets 23 canbe prewelded to the side panels 14, and different size top sheets 19prewelded to one of the side panels 14, and then the assembly completedout of inventory depending upon what final tunnel width is desired. Ofcourse, besides varying the width of the chassis, it is also very easyto vary the length by changing the length of the parts l4, l9 and 23.

It was stated previously that the casting sides 12 and side panels 14reinforce each other, and the same is true of the parts 14, 19 and 20 atthe rear end of the tunnel. Also, the corrugations 21 in the top sheet19 stiffens the same. In addition, the ledges 26-28 stiffen the sidepanels, and the front casting 11 has webs or flanges to likewisestrengthen the same. What all this means is that the invention, besidesall the aforementioned advantages, makes it possible to achieve about a10 percent weight reduction and 10-13 percent increase in strength overprior art comparable frames. This is an important advantage of theinvention considering the punishing use to which snowmobiles aresometimes subjected, and that the invention makes it possible toincrease the power to weight ratio without increasing engine size. Theweight saving in the machine is of the order of 45 pounds. Also, theinvention makes it possible to service the machine by readily replacingdamaged parts. In the prior art the front end support was a multi-partsteel structure welded and/or riveted to the frame in such a manner thatit wasnt readily replaceable. Also, the frame was a large single piecesteel stamping so that a damaged portion thereof wasnt replaceable northe undamaged part thereof salvageable. In the invention thesedisadvantages are overcome since the welded or riveted connections canbe readily broken to separate the parts so that the damaged ones can bereplaced or the undamaged ones salvaged.

What I claim to be my invention is:

1. A snowmobile chassis, comprising a modular frame constructed fromlightweight extruded and sheet metal stock and a single piecelightweight metal front end modular ski post support, said modular framecomprising a tunnel having two extruded aluminum side panels, a topaluminum sheet joined to the upper portions of said side panels, a pairof aluminum sheets joined to the lower portions of said side panels toprovide running boards on said tunnel, said ski post support comprisingan integral generally U-shaped aluminum casting having its sides joinedto the front ends of said side panels for reinforcing each other, saidcasting having a pair of integral front diverging ski post supportingarms formed thereon, integral tubular bearings formed in said arms forsupporting a pair of ski posts therein, transverse corrugations formedin said top sheet to stiffen the same, and a pair of aligned bearingapertures formed in the portions of the casting sides and side panelswhich are joined to each other for supporting a snowmobile drive beltshaft therein.

2. In a snowmobile chassis as in claim 1, wherein said modular frame isadapted to have different width top sheets joined to the side panels'tovary the width of said tunnel, and said modular ski post support isadapted to fit different size tunnels by varying the cast width of saidU-shaped aluminum casting, to match up the front end casting with thetunnel.

3. In a snowmobile chassis as in claim 2, wherein the upper and lowerportions of said side panels have inwardly and outwardly directedintegral shouldered ledges formed thereon for nesting the opposite edgesand inner edges of said top and running board sheets therein, and saidledges and edges being spot welded to each other.

4. In a snowmobile chassis as in claim 3, overhanging shoulders formedon the upper portions of said side panels to align said modular ski postsupport and frame with each other, and the sides of said aluminumcasting and side panels being riveted together.

5. In a snowmobile chassis as in claim 3, integral overhanging ledgesformed on the lower portions of said side panels adjacent to theshouldered ledges thereof, said overhanging and shouldered ledges beingspaced from each other by a distance equivalent to the thickness of therunning board sheets, and the inner edges of said running board sheetsbeing nested between said spaced overhanging and shouldered ledges.

6. In a snowmobile chassis as in claim 3, a pair of integral upwardlyslanted foot rests formed on the front ends of said running boardsheets, said foot rests being joined to said side panels, and a backpanel at the rear end of said tunnel, said back panel being joined tosaid side panels and top sheet to reinforce the rear end of said tunnel.

7. A snowmobile chassis modular frame constructed from lightweightextruded and sheet metal stock. said modular frame comprising a tunnelhaving two extruded aluminum side panels, a top aluminum sheet joined tothe upper portions of said side panels, a pair of aluminum sheets joinedto the lower portions of said side panels to provide running boards onsaid tunnel, transverse corrugations formed in said top sheet to stiffenthe same, and said modular frame being adapted to have different widthtop sheets joined to the side panels to very the width of said tunnel.

8. In a snowmobile chassis modular frame as in claim 7, wherein theupper and lower portions of said side panels have inwardly and outwardlydirected integral shouldered ledges form thereon for nesting theopposite edges and inner edges of said top and running board sheetstherein, and said ledges and edges being spot welded to each other.

9. In a snowmobile chassis modular frame as in claim 8, integraloverhanging ledges formed on the lower portions of said side panelsadjacent to the shouldered ledges thereof, said overhanging andshouldered ledges being spaced from each other by a distance equivalentto the thickness of the running board sheets, and the inner edges ofsaid running board sheets being nested between said spaced overhangingand shouldered ledges.

10. In a snowmobile chassis modular frame as in claim 9, a pair ofintegral upwardly slanted foot rests formed on the front ends of saidrunning board sheets, said foot rests being joined to said side panels,and a back panel at the rear end of said tunnel, said back panel beingjoined to said side panels and top sheet to reinforce the rear end ofsaid tunnel.

11. A snowmobile chassis single piece lightweight metal front endmodular ski post support, said ski post support comprising an integralgenerally U-shaped alushaft therein, and said modular ski post supportbeing adapted to fit different size snowmobile chassis frame tunnels byvarying the cast width of said U-shaped aluminum casting, to match upthe front end casting with aligned bearing apertures formed in the sidesof U- the tunnel.

shaped casting for supporting a snowmobile drive belt

1. A snowmobile chassis, comprising a modular frame constructed fromlightweight extruded and sheet metal stock and a single piecelightweight metal front end modular ski post support, said modular framecomprising a tunnel having two extruded aluminum side panels, a topaluminum sheet joined to the upper portions of said side panels, a pairof aluminum sheets joined to the lower portions of said side panels toprovide running boards on said tunnel, said ski post support comprisingan integral generally Ushaped aluminum casting having its sides joinedto the front ends of said side panels for reinforcing each other, saidcasting having a pair of integral front diverging ski post supportingarms formed thereon, integral tubular bearings formed in said arms forsupporting a pair of ski posts therein, transverse corrugations formedin said top sheet to stiffen the same, and a pair of aligned bearingapertures formed in the portions of the casting sides and side panelswhich are joined to each other for supporting a snowmobile drive beltshaft therein.
 2. In a snowmobile chassis as in claim 1, wherein saidmodular frame is adapted to have different width top sheets joined tothe side panels to vary the width of said tunnel, and said modular skipost support is adapted to fit different size tunnels by varying thecast width of said U-shaped aluminum casting, to match up the front endcasting with the tunnel.
 3. In a snowmobile chassis as in claim 2,wherein the upper and lower portions of said side panels have inwardlyand outwardly directed integral shouldered ledges formed thereon fornesting the opposite edges and inner edges of said top and running boardsheets therein, and said ledges and edges being spot welded to eachother.
 4. In a snowmobile chassis as in claim 3, overhanging shouldersformed on the upper portions of said side panels to align said modularski post support and frame with each other, and the sides of saidaluminum casting and side panels being riveted together.
 5. In asnowmobile chassis as in claim 3, integral overhanging ledges formed onthe lower portions of said side panels adjacent to the shouldered ledgesthereof, said overhanging and shouldered ledges being spaced from eachother by a distance equivalent to the thickness of the running boardsheets, and the inner edges of said running board sheets being nestedbetween said spaced overhanging and shouldered ledges.
 6. In asnowmobile chassis as in claim 3, a pair of integral upwardly slantedfoot rests formed on the front ends of said running board sheets, saidfoot rests being joined To said side panels, and a back panel at therear end of said tunnel, said back panel being joined to said sidepanels and top sheet to reinforce the rear end of said tunnel.
 7. Asnowmobile chassis modular frame constructed from lightweight extrudedand sheet metal stock, said modular frame comprising a tunnel having twoextruded aluminum side panels, a top aluminum sheet joined to the upperportions of said side panels, a pair of aluminum sheets joined to thelower portions of said side panels to provide running boards on saidtunnel, transverse corrugations formed in said top sheet to stiffen thesame, and said modular frame being adapted to have different width topsheets joined to the side panels to very the width of said tunnel.
 8. Ina snowmobile chassis modular frame as in claim 7, wherein the upper andlower portions of said side panels have inwardly and outwardly directedintegral shouldered ledges form thereon for nesting the opposite edgesand inner edges of said top and running board sheets therein, and saidledges and edges being spot welded to each other.
 9. In a snowmobilechassis modular frame as in claim 8, integral overhanging ledges formedon the lower portions of said side panels adjacent to the shoulderedledges thereof, said overhanging and shouldered ledges being spaced fromeach other by a distance equivalent to the thickness of the runningboard sheets, and the inner edges of said running board sheets beingnested between said spaced overhanging and shouldered ledges.
 10. In asnowmobile chassis modular frame as in claim 9, a pair of integralupwardly slanted foot rests formed on the front ends of said runningboard sheets, said foot rests being joined to said side panels, and aback panel at the rear end of said tunnel, said back panel being joinedto said side panels and top sheet to reinforce the rear end of saidtunnel.
 11. A snowmobile chassis single piece lightweight metal frontend modular ski post support, said ski post support comprising anintegral generally U-shaped aluminum casting, said casting having a pairof integral front diverging ski post supporting arms formed thereon,integral tubular bearings formed in said arms for supporting a pair ofski posts therein, a pair of aligned bearing apertures formed in thesides of U-shaped casting for supporting a snowmobile drive belt shafttherein, and said modular ski post support being adapted to fitdifferent size snowmobile chassis frame tunnels by varying the castwidth of said U-shaped aluminum casting, to match up the front endcasting with the tunnel.